The invention relates to a security system for a motor vehicle opening leaf.
The invention relates more specifically to a security system for an opening leaf of a motor vehicle of the type in which the opening leaf is held in the closed position by a lock which is operated by means of a handle arranged on the outside of a bodywork panel of the opening leaf, of the type in which the security system comprises means for detecting, remotely, by means of an electromagnetic signal, the presence of a user's hand near the handle, and of the type in which the detection means comprise a control circuit and at least one sensor capable of emitting or of receiving the electromagnetic signal.
Such a system is described, for example, in document FR-A-2,733,783. The system described in this document proposes the use, as a means of detecting the presence of the hand, of an infrared-radiation sensor. This sensor "observes" an area in space around the handle so that when a user's hand approaches it, the infrared radiation emitted by the hand is picked up and analyzed by the sensor which is then capable of transmitting control information to an antitheft unit.
However, the invention can also be implemented in the context of a security system in which the detection means comprise an emitter which emits an electromagnetic signal intended to be received by a receiver, the path of the signal between the emitter and the receiver running, at least in part, on the outside of an external panel of the opening leaf. In this case, the presence of the hand is detected when the hand intercepts the path of the signal because, at that instant, the signal is no longer received by the receiver.
In this case, the signal may, for example, be infrared radiation.
In such a system, it is therefore necessary for the sensor or sensors to be able to "see" the environment on the outside of the handle. However, there is good cause to ensure that the detection means circuit should itself be arranged on the inside of the bodywork panel of the opening leaf, for obvious esthetic reasons.